We aim to identify and purify the molecules elaborated by certain biologically active T cell hybridoma lines which have specific reactivities with antigen or anti-idiotype antibodies. We then wish to map the genes which encode the responsible molecules. We will employ affinity chromatography and immunospecific purification techniques followed by SDS-PAGE to determine the type and number of polypeptide subunits of these molecules. Somatic cell genetics and recombinant DNA techniques will be used to determine whether the genes which encode these molecules are linked to the V(H) cluster.